<template>
    <div>
        <router-link 
            tag="div" 
            to="/" 
            class="header-abs"
            v-show="showAbs"
        >
            <div class="iconfont header-abs-back">&#xe624;</div>
        </router-link>
        <div 
            class="header-fixed" 
            v-show="!showAbs"
            :style="opacityStyle"
        >
            <router-link to="/">
                <div class="iconfont header-fixed-back">&#xe624;</div>
            </router-link>
            景点详情
        </div>
    </div>
</template>

<script>
export default {
    name: 'DetailHeader',
    data() {
        return{
            showAbs: true,
            opacityStyle: {
                opacity: 0
            }
        }
    },
    methods: {
        handleScroll () {
            const top = document.documentElement.scrollTop
            if (top > 60) {
                let opacity = top / 140
                opacity = opacity > 1 ? 1: opacity
                this.opacityStyle = {
                    opacity
                }
                this.showAbs = false
            }else {
                this.showAbs = true
            }
        }
    },
    activated () {
        window.addEventListener('scroll',this.handleScroll)
    },
    deactivated () {
        window.removeEventListener('scroll',this.handleScroll)
    }
}
</script>

<style lang='stylus' scoped>
@import '~styles/varibles.styl'
    .header-abs
        position: absolute
        left: .2rem
        top: .2rem
        height: .8rem
        width: .8rem
        border-radius: .4rem
        background: rgba(0,0,0,0.8)
        .header-abs-back
            color: #fff
            text-align: center
            font-size: .4rem
            line-height: .8rem
    .header-fixed
        z-index: 2
        position: fixed
        height: $headerHeight
        top: 0
        left: 0
        right: 0
        line-height: $headerHeight
        overflow: hidden
        text-align: center
        color: #fff
        background: $bgColor
        .header-fixed-back
            position: absolute
            width: .64rem
            left: 0
            color: #fff
</style>
